Protein methylation and acetylation are common posttranslational modification that mostly occurs on arginine or lysine residues. Arginine methylation has been reported to regulate RNA processing, gene transcription, DNA damage repair, protein translocation, and signal transduction. Lysine methylation is best known to regulate histone function and is involved in epigenetic regulation of gene transcription.
Protein methyltransferases and demethylases have been implicated in human health and disease (Greer, E. L., and Shi, Y. (2012) Histone methylation: a dynamic mark in health, disease and inheritance. Nature Reviews. Genetics 13, 343-357; Yang, Y, and Bedford, M. T. (2013) Protein arginine methyltransferases and cancer. Nature Reviews. Cancer 13, 37-50). Considering the important biological roles of protein methylation, there is a need for identification of additional methylated proteins and methylation sites.